The two cochlear implant users tested showed strong effects of ILDs in various broadband stimuli with respect to JNDs as well as lateralization position. The high dependency of ILD-JNDs on the interaural pitch difference suggests the potential importance of pitch-matched assignment of electrodes in the two ears by the speech processors. Envelope ITDs appear to be more ambiguous cues than ILDs, as reflected by the higher and more variable JNDs compared with normal-hearing listeners. The envelope ITD-JNDs of cochlear implant listeners depended on the stimulus.

The envelope shape is important for the perception of interaural time difference (ITD) in the envelope as supported by the improved sensitivity for transposed tones compared to sinusoidally amplitude-modulated (SAM) tones. The present study investigated the effects of specific envelope parameters in nine normal-hearing (NH) and seven cochlear-implant (CI) listeners, using high-rate carriers with 27-Hz trapezoidal modulation. In NH listeners, increasing the off time (the silent interval in each modulation cycle) up to 12 ms, increasing the envelope slope from 6 to 8 dB/ms, and increasing the peak level improved ITD sensitivity. The combined effect of the off time and slope accounts for the gain in sensitivity for transposed tones relative to SAM tones. In CI listeners, increasing the off time up to 20 ms improved sensitivity, but increasing the slope showed no systematic effect. A 27-pulses/s electric pulse train, representing a special case of modulation with infinitely steep slopes and maximum possible off time, yielded considerably higher sensitivity compared to the best condition with trapezoidal modulation. Overall, the results of this study indicate that envelope-ITD sensitivity could be improved by using CI processing schemes that simultaneously increase the off time and the peak level of the signal envelope.

Both open-fit HAs and AMEIs provided audiologic benefit to patients with sloping high-frequency sensorineural hearing loss. However, despite overlapping indication criteria for the 2 devices, performance with the AMEI was significantly better for the AMEI than for the open-fit HA.

The AMEI system VSB can be considered as an effective rehabilitation alternative in subjects with mild-to-severe SNHL and unsatisfying benefit from conventional hearing aids.